1. Field of the Invention
The present invention relates to a digital broadcast receiving system and, in particular, to a digital broadcast receiving system having a function of recording and reproducing a digital information.
2. Description of the Background Art
FIG. 22 is a block diagram showing, only in simplified form, the configuration of a conventional digital broadcast receiving system as disclosed in Japanese Patent Application Laid-Open No. 9-247603 (1997). Referring to FIG. 22, this digital broadcast receiving system comprises a receiver 102, monitor 104, and record and reproduction unit 103. The receiver 102 comprises a receive and demodulation section 111, packet filter 112, controller 123, information table extractor 114, information table replacement unit 124, record and reproduction information table generator 126, digital interface 122, circuit changing switch 117, demultiplexer 118, and AV decoder 119. The record and reproduction unit 103 comprises a digital interface 131, information table extractor 132, controller 140, deck 135, and buffer 136.
Operation of the conventional digital broadcast receiving system shown in FIG. 22 will be explained hereinafter. The receive and demodulation section 111 demodulates the received digital broadcast signals. The information table extractor 114 extracts, from the digital broadcast signals, an NIT (Network Information Table) that is the network related information table, a PAT (Program Association Table) that is the information table related to the program of each channel, namely the entire information of the sent program, a PMT (Program Mapping Table) that is the information on the packet configuration of each program, and an EIT (Event Information Table) that is the detailed information of each program. These tables are multiplexed and transmitted in the digital broadcast signals, according to MPEG-2 system.
The controller 123 creates, based on the extracted information table, the information on the received plural programs, to inform it to the user. From these programs, the user selects the program that it is desired to record, and its result is sent to the controller 123. Based on the information table, the controller 123 designates the packet related to the program to be recorded, and its result is sent to the packet filter 112. The packet filter 112 selects the designated packet and then outputs it via the information table replacement unit 124 to the digital interface 122. The controller 123 also extracts much information on the program recorded (e.g., the broadcast start day and time, program name, and information indicating the kind of each stream in the digital broadcast signals received), from the descriptors in the extracted PMT and NIT.
The record and reproduction information table generator 126 collects much information extracted by the controller 123, and generates a record and reproduction information table in a MPEG-2 transport packet format, and, in a table format having a predetermined MPEG-2 table ID. The information table replacement unit 124 replaces an NIT in the various information tables sent from the packet filter 112, with a record and reproduction information table. The information table replacement unit 124 also rewrites a PAT and a PMT so as to contain only the information on the program and packet selected by the packet filter 112. Digital television signals after being subjected to a packet selection and table rewriting are outputted via the digital interface 122 to the record and reproduction unit 103.
When the record and reproduction unit 103 receives the digital television signals from the digital interface 131, a record and reproduction information table is extracted by the information table extractor 132. The controller 140 acquires much information on the program from the extracted information table. The controller 140 also inputs digital television signals via the buffer 136 to the deck 135, and the deck 135 records the signals in a recording medium.
When the recorded program is reproduced, the record and reproduction unit 103 demodulates the reproduction signals read out of the recording medium by using the deck 135, and outputs it via the buffer 136 to the digital interface 131. When the receiver 102 receives the digital television signals from the digital interface 122, a record and reproduction information table is extracted by the information table extractor 114. The controller 123 acquires much information on the program, from the extracted information table. The controller 123 also switches the circuit changing switch 117 to the digital interface 122 side. Based on the extracted information, the controller 123 directs the demultiplexer 118 to perform a packet selection of the digital broadcast signals. According to the instruction from the controller 123, the demultiplexer 118 separates the digital broadcast signals and inputs it to the AV decoder 119. The AV decoder 119 decodes the data and reproduces it on the monitor 104.
In this digital broadcast receiving system, however, the NIT that is defined by MPEG standard is altered for use as a table in its own format. Therefore, if it is desired to output again the recorded information data to other external unit, which results in the output of a nonstandard stream. In the event that the external unit cannot process the information data of its own format, there is the problem that the program cannot be reproduced.
In addition, the information needed in program recording and reproduction and, in particular, the program array information on the digital broadcast signals to be sent, has any value in those which are defined on the sending side, and is scattered in a plurality of information tables. Therefore, in the program recording and reproduction, a time lag for information extraction occurs, and thus a time lag occurs between the issue of a reproduction start command and the reproduction of the program, thereby making it difficult to process the information data rapidly and from the beginning.
Furthermore, in order that the program can be watched and listened from an arbitrary point of time during its broadcast, as a program array information, the information containing the same contents is sent repetitively and redundantly. Thus, with the conventional digital broadcast receiving system, such redundant data is directly recorded in the record and reproduction unit, thereby wasting a limited recording capacity.